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Oass\.  V^  A_^iT:_ 


Publications 


OF 


FIELD  MUSEUM  OF  NATURAL 

HISTORY 


ZOOLOGICAL  SERIES 


Volume  X 


Chicago,  U.  S.  A. 
iQog  - 1923 


7/ 
,5 


DIAGNOSES   OF   NEW    EAST  AFRICAN    MAMMALS, 
INCLUDING   A   NEW   GENUS   OF   MURID/E. 


BY    WILFRED    H.   OSGOOD, 

ASSISTANT   CURATOR  OF  MAMMALOGY  AND   ORNITHOLOGY. 


The  following  brief  descriptions  are  published  in  advance  of  a 
detailed  report,  now  in  preparation,  on  the  Field  Museum's  expedi- 
tion to  British  East  Africa  in  1905-6.  Through  the  courtesy  of  the 
officials  of  the  British  Museum,  especially  Mr.  Oldfield  Thomas,  it  has 
been  possible  to  make  direct  comparisons  with  types  and  authenticated 
specimens  of  previously  described  species.  The  liberality  of  Mr. 
Thomas,  himself  at  work  on  East  African  collections,  in  freely 
advising  as  well  as  in  giving  access  to  material,  is  most  gratefully 
acknowledged. 

Procavia  mackinderi  zelotes  subsp.  nov. 

Type  from  between  Naivasha  and  Kijabe,  British  East  Africa. 
No.  17475,  Field  Museum  of  Natural  History.  Adult  male  (stage 
VIII).     Collected  January  27,  1906,  by  C.  E.  Akeley. 

Characters.  Similar  to  Procavia  mackinderi  but  smaller;  pelage 
shorter  and  harsher;  subterminal  zone  of  color  on  hairs  of  shoulders 
and  back  narrower  and  darker.  Similar  to  Procavia  jacksoni  in  color 
but  widely  different  in  cranial  characters ;  skull  shorter  and  broader 
throughout;  nasals  shorter;  temporal  fossae  more  extended  posteri- 
orly;  molariform  teeth  much  larger  and  more  hypsodont. 

Measurements.  Average  of  6  adults  from  Kijabe,  measured  in  the 
flesh  by  E.  Heller:  Total  length  470  (420-530);  ear  32.6  (30.5-38); 
hind  foot  (c.  u.)  63.5  (60-68).  Skull  of  type:  Basal  length  89.5; 
basilar  length  78;  zygomatic  breadth  53.2;  nasals  22.5x23.4; 
breadth  between  extremities  of  postorbital  processes  38.8;  dias- 
tema 8.4;  maxillary  toothrow  (crowns)  40;  greatest  width  of  mJ-  7, 
of  m-  8.4. 

Remarks.  Procavia  slatini  Sassi  is  evidently  closely  allied  to  P. 
mackinderi  and  the  present  form  but  no  specimens  representing  it 
have  been  available  for  comparison.  Since  another  form  of  the 
same  group  is  known  from  the  region  intervening  between  the  type 
locality  of  slatini  and  that  of  zelotes,  it  seems  safe  to  assume  that 
the  two  forms  are  well  differentiated. 

S 


6       Field  Museum  of  Natural  History  —  Zoology,  Vol.  X. 

Procavia  brucei  maculata  subsp.   nov. 

Type  from  Lukenya  Mountain,  British  East  Africa.  No.  17504, 
Field  Museum  of  Natural  History.  Adult  male  (stage  VIII).  Col- 
lected December  18,  1905,  by  C.  E.  Akeley. 

Characters.  Similar  to  Procavia  brucei  and  Procavia  brucei 
hindei  but  color  paler  and  more  grayish  throughout;  underparts 
much  less  suffused  with  creamy  or  bufify,  often  nearly  pure  white; 
ears  more  whitish;  dorsal  spot  almost  entirely  pure  white;  upper- 
parts  more  distinctly  spotted  than  in  any  other  member  of  the 
brucei  group,  the  dark  spots  in  one  specimen  numbering  between  40 
and  50  and  extending  from  the  rump  to  the  shoulders.  Skull  most 
similar  to  that  of  hindei,  differing  from  that  of  typical  brucei  in  the 
character  of  the  basisphenoid  which  is  broad  and  rounded  on  its 
lower  surface  instead  of  being  narrow  and  laterally  channeled;  nasals 
broader  and  less  emarginate  behind  than  in  brucei;  audital  bullae 
smaller  than  in  hindei. 

Measurements.  Collector's  measurements  of  an  adult  male: 
Total  length  465;  ear  31.5;  hind  foot  (c.  u.)  60.  Skull  of  type: 
Basal  length  79.7;  basilar  length  70;  zygomatic  breadth  46.5; 
nasals  21.2  x  19.5;  breadth  between  extremities  of  postorbital  proc- 
esses 36.3;  diastema  10.4;  maxillary  toothrow  31.7;  greatest 
width  of  m^  5.4. 

Dendromus  ochropus  sp.  nov. 

Type  from  Lake  Elementeita,  British  East  Africa.  No.  167 15, 
Field  Museum  of  Natural  History.  Adolescent  male.  Collected 
February  11,  1906,  by  E.  Heller. 

Characters.  i\llied  to  Dendroi-nus  mesonielas  and  its  relatives, 
but  having  the  feet,  ears,  and  underparts  chiefly  ochraceous.  Upper- 
parts  dull  ochraceous,  the  subterminal  zone  of  color  being  relatively 
narrow  and  considerably  mixed  with  dusky,  producing  a  slightly 
olivaceous  effect ;  black  dorsal  stripe  well  developed ;  a  small  blackish 
marking  on  the  inside  of  the  hind  leg  just  above  the  tarsal  joint; 
underparts  pale  ochraceous  except  a  patch  of  forwardly  directed 
white  hairs  on  the  throat;  ears  well  clothed  inside  and  out  with 
bright  ochraceous  hairs ;  fore  and  hind  feet  ochraceous  except  the  toes 
which  are  whitish.  Somewhat  similar  to  Dendromus  nyikcB  but 
pelage  coarser,  longer,  and  duller  in  color;  ears  ochraceous  instead 
of  dusky;  feet  and  underparts  ochraceous  instead  of  white;  tail 
bicolor  instead  of  blackish  all  around.  Skull  .slightly  smaller  than 
in  nyikce,  with  smaller  bullae  and  shorter  palatine  slits. 

Measurements.     Type:     Total   length    167;     head   and   body    71; 


Feb.,  1910.     New  East  African  Mammals  —  Osgood.  7 

tail  vertebras  96;  hind  foot  (c.  u.)  19.  Skull  of  type:  Greatest  length 
20.4;  basilar  length  14.6;  zygomatic  breadth  10.7;  nasals  7.1; 
palatine  slits  4.1;    maxillary  toothrow  3.3;    length  of  m^-  2. 

Dendromus  nairobse  sp.  nov. 

Type  from  Nairobi,  British  East  Africa.  No.  16709,  Field 
Museum  of  Natural  History.  Old  male.  Collected  November  6, 
1905,  by  E.  Heller. 

Cltaracters.  Allied  to  Dendromus  ochropus  and  D.  nyikce  but  tail 
shorter  and  color  much  brighter;  upperparts  bright  tawny,  with  the 
black  dorsal  stripe  sharply  contrasted;  zone  of  tawny  color  relatively 
wide;  underparts  pale  creamy  whitish;  ears  pale  ochraceous;  feet 
white,  slightly  touched  with  fulvous ;  tail  distinctly  bicolor ;  inner  side  of 
hind  leg  without  dusky  spot  above  tarsal  joint.  Skull  very  broad, 
with  heavy,  angled  zygomata,  the  zygomatic  breadth  slightly  greater 
anteriorly  than  posteriorly. 

Measuretnents.  Type:  Total  length  163  ;  head  and  body  83  ;  tail 
vertebras  85;  hind  foot  (c.  u.)  18;  ear  14.  Skull  of  type:  Zygomatic 
breadth  11.6;  nasals  8;  palatine  slits  3.9;  maxillary  toothrow  3; 
length  of  m  ^-  1.7. 

Dendromus  vvhytei  pallescens  subsp.  nov. 

Type  from  Lukenya  Mountain,  British  East  Africa.  No.  167 10, 
Field  Museum  of  Natural  History.  Adult  male.  Collected  Decem- 
ber 28,   1905,  by  E.  Heller. 

Characters.  Similar  to  Dendromus  whytei  but  paler;  general 
color  of  upperparts  pale  buffy  ochraceous  instead  of  tawny;  under- 
parts creamy  white ,  nearly  pure  white  on  chin  and  throat ;  facial 
region  without  dusky  markings;  dorsal  stripe  obsolescent,  consisting 
of  an  indistinct  narrow  line  of  dusky-tipped  hairs  mixed  with  fulvous. 

Measurements.  Type  and  one  topotype,  respectively:  Total 
length  147,  137;  head  and  body  69,  60;  tail  vertebrae  78,  77;  hind 
foot  (c.  u.)  15.5,  16;  ear  11. 2,  Skull  of  type:  Greatest  length  19.8; 
basilar  length  14.8;  zygomatic  breadth  10.3;  nasals  7.2;  palatine 
slits  3.7;   maxillary  toothrow  3;   length  of  m^-  1.8. 

Zelotomys  gen.  nov. 

Type.     M us  hilde gar decc  Thomas  {=Zelotomys  hildegardece) . 

Characters.  Size  medium  (hind  foot  22-24);  tail  shorter  than 
head  and  body;  ear  moderate,  rounded;  mammge  2-2  =  8.  Skull 
short  and  broad;  braincase  very  short;  frontals  but  little  expanded 
posteriorly,  their  supraorbital  boundaries  smoothly  rounded;    nasals 


8      Field  Museum  of  Natural  History  —  Zoology,  Vol.  X. 

extended  posteriorly  beyond  anterior  root  of  zygoma  and  ending 
about  on  the  plane  of  the  middle  of  the  first  upper  molar;  inter- 
parietal very  small.  Molars  very  broad  and  more  hypsodont  than 
in  Mus;  first  upper  molar  longer  than  second  and  third  combined; 
second  upper  molar  broader  than  long  and  very  obliquely  set  in  tooth- 
row  ;  cusps  of  molars  numerically  as  in  Mus;  upper  incisors  decidedly 
projecting. 

Thamnomys  surdaster  polionops  subsp.  nov. 

Type  from  Lukenya  Mountain,  British  East  Africa.  No.  17 112, 
Field  Museum  of  Natural  History.  Adult  male.  Collected  Decem- 
ber 20,  1905,  by  E.  Heller. 

Characters.  Similar  to  Thamnomys  surdaster  but  less  tawny  on  the 
sides  from  the  nose  to  the  flanks;  sides  of  face,  arms,  and  sides  of  body 
more  or  less  olivaceous  gray  with  slight  mixture  of  tawny;  a  distinct 
dusky  area  from  the  eye  to  the  base  of  the  whiskers;  upperparts 
bright  tawny  as  in  surdaster.  Skull  much  as  in  surdaster,  but  averag- 
ing slightly  larger  and  broader.  Distinguished  from  Thamnomys 
dryas  by  the  possession  of  6  mammae  instead  of  4;  from  T.  mac- 
millani  by  larger  size  and  darker  color;  from  T.  ibeanus  by  smaller 
size,  smaller  ears,  brighter  color,  and  paler  under  sides  of  hind  legs. 

Measurements.  Type:  Total  length  284;  head  and  body  120; 
tail  vertebrae  164;  hind  foot  (s.  u.)  24;  ear  16.  Skull  of  type:  Great- 
est length  30.4;  basilar  length  22.9;  zygomatic  breadth  14.3 ;  nasals 
11;  least  interorbital  breadth  4.5;  postpalatal  length  10.5  ;  diastema 
7.4;   palatine  slits  6.8;   maxillary  toothrow  4.5. 

Thamnomys  ibeanus  sp.  nov. 

Type 'from  Molo,  British  East  Africa.  No.  17096,  Field  Museum 
of  Natural  History.  Adult  male.  Collected  March  15,  1906,  by 
E.  Heller. 

Characters.  Size  large;  color  dark  and  relatively  dull;  hind  legs 
just  above  tarsal  joint  usually  dark-colored  all  around;  skull  and 
teeth  relatively  large.  Most  similar  to  Thamnomys  dolichurus  but 
color  darker;  size  larger;  teeth  sHghtly  larger ;  audital  bullae  smaller. 
Somewhat  similar  to  T.  surdaster  and  T.  s.  polionops  but  size  larger 
and  color  duller;  skull  and  teeth  larger;  audital  bullae  relatively 
small,  about  equalling  those  of  polionops  in  actual  size. 

Measurements.     Type:    Total  length   329;    head  and  body   136; 

tail  vertebrae  193;   hind  foot  (s.  u.)  26;    ear  21.     Average  of  8  adults 

from  Molo,  Gilgil,  and  Lake  Elementeita:   Total  length  305  (290-330) ; 

.  head  and  body  121  (109-136);  tail  vertebras  184  (174-204);  hind  foot 


Feb.,  1910.     New  East  African  Mammals  —  Osgood.  9 

(s.  u.)  25.3  (24-26.5);  ear  20.7  (19-22).  Skull  of  type  and  an  adult 
from  Lake  Elementeita,  respectively:  Greatest  length  32.7,  31.8; 
basilar  length  25.3,  24.4;  zygomatic  breadth  15.9,  14-9;  nasals  11. 9, 
12.3;  least  interorbital  breadth  5,  4.7;  postpalatal  length  11.8,  11.2; 
diastema  8.4,  8;    palatine  slits  7.8,  7.2;   maxillary  toothrow  5.1,  4.6. 

Cricetomys  gambianus  kenyensis  subsp.  nov. 

Type  from  south  side  of  Mount  Kenya,  British  East  Africa.  No. 
17517,  Field  Museum  of  Natural  History.  Adult  male.  Collected 
by  C.  E.  Akeley. 

Characters.  Most  similar  to  Cricetomys  gambianus  proparator 
but  proximal  dark  color  of  tail  more  extensive,  occupying  at  least 
three-fifths  of  the  length  of  the  tail;  color  of  upperparts  somewhat 
paler  especially  on  the  sides  which  are  more  contrasted  with  the  back. 
Skull  slightly  larger  than  in  proparator;  nasals  broader  posteriorly, 
their  outer  sides  nearly  parallel;  rostrum  slightly  thicker  dorso- 
ventrally;  infraorbital  plate  narrower  and  less  forwardly  projecting. 
Somewhat  similar  to  C.  g.  viator  but  much  darker  in  color,  with  a  more 
marked  dorsal  area. 

Measurements.  Skull  of  type:  Greatest  length  76.3;  basilar 
length  62.6;  zygomatic  breadth  36.5;  least  interorbital  breadth  12; 
nasals  31;  postpalatal  length  25.5;  diastema  25;  palatine  slits  8; 
maxillary  toothrow  11.3. 

Otomys  thomasi  sp.  nov. 

Type  from  Molo,  British  East  Africa.  No.  16698,  Field  Museum 
of  Natural  History.  Adult  female.  Collected  March  16,  1906,  by 
E.  Heller. 

Characters.  Allied  to  Otomys  irroratns  tropicalis  and  other  species 
having  narrow  nasals  and  m-i  with  seven  laminae,  but  color  widely 
different  and  skull  decidedly  arched  or  "humped."  Dominant 
color  of  upperparts  varying  from  pale  cinnamon  to  wood  brown  in- 
stead of  rich  hazel  as  in  tropicalis;  a  rather  conspicuous  patch  of 
creamy  buff  behind  the  ears;  fore  and  hind  feet  entirely  creamy  buff; 
underparts  wood  brown. 

Measurements.  Type  and  one  topotype,  respectively:  Total 
length  282,  283;  head  and  body  184,  180;  tail  vertebrae  98,  103;  hind 
foot  (s.  u.)  30.5,  31;  ear  24,  23.5.  Skull  of  type:  Greatest  length 
43.3;  basilar  length  34.6;  zygomatic  breadth  21.7;  length  of  nasals 
20.7;  greatest  breadth  of  nasals  7.5;  least  interorbital  breadth  3.4; 
depth  from  highest  point  of  orbit  to  alveolar  border  at  front  of  m^ 
14.5;  postpalatal  length  1 5.1 ;  palatine  slits  7.5 ;  maxillary  toothrow 
9.2;   greatest  width  of  m^-  2.5. 


lo     Field  Museum  of  Natural  History  —  Zoology,  Vol.  X. 

Otomys  angoniensis  elassodon  subsp.  nov. 

Type  from  Naivasha,  British  East  Africa.  No.  16684,  Field  Mu- 
seum of  Natural  History.  Adult  female.  Collected  January  29, 
1906,  by  E.  Heller. 

Characters.  Similar  to  Otomys  angoniensis,  but  paler  and  more 
grayish;  molars  narrower;  nasals  broadly  expanded;  m'^  with  seven 
laminae.  Distinguished  from  Otomys  nyikce  canescens  by  slightly 
darker  color  but  especially  by  more  elongate  skull,  narrower  brain- 
case,  and  narrower  molars. 

Measurements.  Type:  Total  length  270;  head  and  body  183; 
tail  vertebrae  87;  hind  foot  (c.  u.,  dry)  29;  ear  21.  Skull  of  type: 
Greatest  length  41;  basilar  length  34-3;  zygomatic  breadth  21; 
length  of  nasals  17.7;  greatest  breadth  of  nasals  8.9;  least  inter- 
orbital  breadth  4.5;  depth  from  highest  point  of  orbit  to  alveolar 
border  at  front  of  m^  13.8;  postpalatal  length  15;  palatine  slits  8; 
maxillary  toothrow  8.2;    greatest  width  of  mi-  2.4. 

Otomys  nyikae  canescens  subsp.  nov. 

Type  from  Kijabe,  British  East  Africa.  No.  16682,  Field  Museum 
of  Natural  History.  iVdult  male.  Collected  January  20,  1906,  by 
E.    HeUer. 

Characters.  Similar  in  size  and  cranial  characters  to  Otomys 
nyikce,  but  color  much  paler  and  grayer;  general  effect  of  upperparts 
grizzled  wood  brown  or  broccoli  brown  instead  of  deep  russet ;  nasals 
broadlv  expanded  anteriorly;  m^  with  seven  laminae.  Color  much 
as  in  Otomys  a.  elassodon,  but  slightly  more  grayish;  skull  shorter 
and  broader;    molars  wider. 

Measurements.  Type  and  two  topotypes,  respectively.  Total 
length  259,  255,  242;  head  and  body  175,  165,  157;  tail  vertebrae 
84,  90,  85;  hind  foot  29,  30,  .^7.5;  ear  19.5,  21,  20.  Skull  of  type: 
Greatest  length  37.2;  basilar  length  30.9;  zygomatic  breadth  19.6; 
length  of  nasals  17.1;  greatest  breadth  of  nasals  8.5;  least  inter- 
orbital  breadth  4.6;  depth  from  highest  point  of  orbit  to  alveolar 
border  at  front  of  m'^  12.8;  postpalatal  length  13.8;  palatine  shts 
6.8;   maxillary  toothrow  8.4;   greatest  width  of  m-i  2.6. 

Arvicanthis  barbarus  convictus  subsp.  nov. 

Type  from  Voi,  British  East  Africa.  No.  17206,  Field  Museum 
of  Natural  History.  Adult  male.  Collected  April  16,  1906,  by 
E.    Heller. 

Characters.  Allied  to  Arvicanthis  barbarus  spekei,  A.  b.  zebra  and 
other  forms  having  unbroken  stripes.     Size  about  as  in  spekei  but 


Feb..  1910.     New  East  African  Mammals  —  Osgood.  ii 

color  decidedly  more  rufescent.  Light  stripes  pale  ochraceous  buflF 
and  numbering  5-6  of  the  heavier  or  primary  ones  and  4-5  of  the 
secondary  ones  on  each  side.  Four  definite  primary  dark  stripes  on 
each  side,  each  divided  by  a  secondary  light  stripe.  Ears  bright 
cinnamon  rufous;  upper  side  of  fore  and  hind  feet  ochraceous  buff; 
underparts  creamy  buff.  Skull  much  as  in  spekei  but  molars  slightly 
smaller;  larger  and  more  elongate  than  in  zebra  and  albolineatus. 

Measurements.  Type:  Total  length  228;  head  and  body  104 
tail  vertebrae  124;  hind  foot  (c.  u.)  26;  ear  14.5.  Skull  of  type 
Greatest  length  29.9;  basilar  length  23.2;  zygomatic  breadth  13.6 
nasals  11. 2;  least  interorbital  breadth  4.5;  postpalatal  length  10.7 
diastema  6.7;    palatine  slits  5.8;    maxillary  toothrow  5.2. 

Arvicanthis  barbarus  albolineatus  subsp.  nov. 

Type  from  Lukenya  Mountain,  British  East  Africa.  No.  17194, 
Field  Museum  of  Natural  History.  Adult  female.  Collected  De- 
cember 14,   1905,  by  E.  Heller. 

Characters.  Most  similar  to  Arvicanthis  barbarus  zebra  but  paler 
with  lighter,  more  whitish  stripes  and  decidedly  paler  c'rs.  Some- 
what similar  to  A.  b.  spekei  but  smaller  with  paler  stripes,  paler  ears, 
and  smaller  molars.  Arrangement  of  stripes  about  as  in  zebra  and 
convictus;  light  dorsal  stripes  pale  creamy,  those  on  the  sides  still 
lighter,  almost  white;  median  dark  stripe  extending  forward  beyond 
the  ears;  forehead  and  sides  of  face  coarsely  grizzled  creamy;  ears 
buff  or  cream  buff  instead  of  ochraceous  or  tawny  as  in  allied  forms; 
fore  and  hind  feet  buffy  white.  Skull  with  relatively  short  broad 
braincase,  small  molars,  and  good-sized  audital  bullae. 

Measurements.  Type:  Total  length  216;  head  and  body  102; 
tail  vertebras  114;  hind  foot  (c.  u.)  24;  ear  13.  Skull  of  type:  Great- 
est length  27.6;  basilar  length  21. i;  zygomatic  breadth  13. i;  nasals 
II. I ;  least  interorbital  breadth  4.3;  postpalatal  length  9.3;  dias- 
tema 6.5;    palatine  slits  5.3;    maxillary  toothrow  5.1. 

Mus  voi  sp.  nov. 

Type  from  Voi,  British  East  Africa.  No.  17062,  Field  Museum 
of  Natural  History.  Adult  male.  Collected  April  22,  1906,  by 
E.    Heller. 

Characters.  Allied  to  Mus  chrysophilus  but  duller  in  color;  gen- 
eral tone  of  upperparts  dull  russet  rather  than  bright  ochraceous; 
skull  with  more  slender  nasals,  lighter  and  narrower  zygomatic  plate, 
slightly  smaller  audital  bulls,  and  shghtly  smaller  molars.  Upper- 
parts  dull  russet  brightening  on  the  sides  and  face  to  tawn}^  ochra- 


12     Field  Museum  of  Natural  History  —  Zoology,  Vol.  X. 

ceous;  a  slight  dusky  marking  in  front  of  and  narrowly  bordering 
the  anterior  half  of  the  eye;  ears  thinly  clothed  with  tawny  hairs; 
feet  creamy  white;  underparts  creamy  white,  the  hairs  slaty  at  their 
bases;  tail  dusky  all  around,  annulations  lo  per  cm.  Distinguished 
from  Mus  hindei,  to  which  it  has  slight  superficial  resemblance,  by 
its  much  longer  tail  and  its  smaller,  flatter  skull. 

Measurements.  Total  length  315;  head  and  body  154;  tail  ver- 
tebras 161;  hind  foot  (c.  u.)  31;  ear  19.5.  Skull  of  type:  Greatest 
length  36.3;  basilar  length  27.5;  zygomatic  breadth  17.9;  nasals 
14.7;  least  interorbital  breadth  5.2;  postpalatal  length  12.6;  pal- 
atine slits  8.2;    diastema  8.2;    upper  toothrow  6.1. 

Mus  niveiventris  sp.  nov. 

Type  from  Voi,  British  East  Africa.  No.  17099,  Field  Museum 
of  Natural  History.  Adult  female.  Collected  April  22,  1906,  by 
E.    Heller. 

Characters.  Allied  to  Mus  verreauxi  and  Mus  hrockmdni;  tail 
decidedly  longer  than  head  and  body;  mammae  3-2  =  10.  Tail 
shorter  than  in  brockmani  -and  color  of  upperparts  very  much  darker. 
Slightly  smaller  than  verreauxi;  tail  shorter;  underparts  entirely 
white  with  hairs  white  instead  of  slaty  basally;  skull  smaller  with 
relatively  larger  molars.  Upperparts  mixed  buff  or  ochraceous  buff 
and  dusky  producing  a  general  effect  of  dull  cinnamon  to  wood  brown, 
in  much  worn  pelage  clear  Mars  brown;  ears  practically  naked  except 
near  the  edges  where  they  are  very  thinly  clothed  with  whitish  hairs ; 
underparts  entirely  creamy  white  to  the  roots  of  the  hairs;  dusky 
orbital  very  slight  and  scarcely  evident. 

Measurements.  Type:  Total  length  262;  head  and  body  109; 
tail  vertebree  153;  hind  foot  (c.  u.)  23;  ear  17.5.  Skull  of  type: 
Greatest  length  30;  basilar  length  23.5;  zygomatic  breadth  14.2; 
nasals  13;  least  interorbital  breadth  4.4;  postpalatal  length  10.2; 
diastema  8.1;    palatine  slits  7;   maxillary  toothrow  4.7. 

Mus  niveiventris  subfuscus  subsp.  nov. 

Type  from  Lake  Elementeita,  British  East  Africa.  No.  16972, 
^ Field  Museum  of  Natural  History.  Adult  male.  Collected  Febru- 
ary 9,  1906,  by  E.  Heller. 

Characters.  Similar  to  Mus.  niveiventris  but  slightly  darker 
colored  above  and  with  hairs  of  underparts  broadly  slaty  at  bases 
except  on  middle  of  chin  and  throat;  skull  essentially  as  in  nivei- 
ventris but  braincase  averaging  broader.  Smaller  and  shorter-tailed 
than  Mus  verreauxi;  skull  smaller;  molars  larger. 


Feb.,  1910.     New  East  African  Mammals  —  Osgood.  13 

Measurements.  Type:  Total  length  257;  head  and  body  105; 
tail  vertebrae  1 48 ;  hind  foot  (c.  u.)  24;  ear  17.  Skull  of  type:  Great- 
est length  29;  basilar  length  22.9;  zygomatic  breadth  14.7;  nasals 
12;  least  interorbital  breadth  4.5;  postpalatal  length  10;  palatine 
slits  6.3;    diastema  7.7;    maxillary  toothrow  4.7. 

Nasilio  brachyrhynchus  albiventer  subsp.  nov. 

Type  from  Lake  Elementeita,  British  East  Africa.  No.  16663, 
Field  Museum  of  Natural  History.  Adult  male.  Collected  Feb- 
ruary 9,  1906,  by  E.  Heller. 

Characters.  Most  similar  to  Nasilio  brachyrhynchus  malosce  but 
underparts  nearly  white  instead  of  buffy;  eye  ring  narrower;  sides 
of  face  without  blackish  markings ;  inside  of  ears  thinly  clothed  with 
whitish  instead  of  ochraceous  hairs;  upper  lip  and  sides  of  "pro- 
boscis" whitish  rather  than  bufiEy;  general  color  of  upperparts  prac- 
tically as  in  malosce,  decidedly  darker  than  in  delamerei. 

Measurements.  Type:  Total  length  224;  head  and  body  116; 
tail  vertebrae  108;  hind  foot  (c.  u.)  31;  ear  22.  Skull  of  type: 
Greatest  length  2>Z-?)'y  basilar  length  31.7;  zygomatic  breadth  18.7; 
nasals  13.5;    least  interorbital  breadth  5.9;    upper  tooth  series  17.4. 


